原文

Though you may have installed the react-native-cli via npm as a separate module, it is a shell for accessing the CLI embedded in the React Native of each project. Your commands and their effects are dependent on the version of the module of react-native in context of the project. This guide will give a brief overview of the CLI in the module.

有可能您已经在电脑上通过npm独立安装了react-native-cli模块，但它本质上是React Native项目中内嵌的CLI工具的一个壳，项目中不同的react-native版本可能导致不同的执行结果。这篇文章只是简单的介绍一下这个CLI。

本地CLI（The local CLI）

React Native has a local-cli folder with a file named cliEntry.js. Here, the commands are read from commands.js and added as possible CLI commands. E.G. the react-native link command, exists in the react-native/local-cli/link folder, and is required in commands.js, which will register it as a documented command to be exposed to the CLI.

React Native的local-cli文件夹中有一个cliEntry.js，从commands.js中读取并将所有的命令添加到CLI中。以react-native link命令为例，存在react-native/local-cli/link文件夹中，commands.js将其引用，随后作为一个文档完善的命令被暴露在CLI中。

命令定义（Command definitions）

At the end of each command entry is an export. The export is an object with a function to perform, description of the command, and the command name. The object structure for the link command looks like so:

在每条命令入口文件的结尾是一个导出对象，包含要调用的函数、命令的描述和命令名字。link命令的对象结构如下所示：

module.exports = {
  func: link,
  description: 'links all native dependencies',
  name: 'link [packageName]',
};

参数（Parameters）

The command name identifies the parameters that a command would expect. When the command parameter is surrounded by greater-than, less-than symbols < >, this indicates that the parameter is expected. When a parameter is surrounded by brackets [ ], this indicates that the parameter is optional.

命令标记了需要的参数。当参数被一对大于号和小于号< >包裹起来时，说明这个参数是必填参数；当参数被一对中括号[ ]包裹起来时，说明这个参数是选填参数。