php根据命令行参数生成配置文件

像npm, composer等工具，在开始使用的使用，都需要初始化项目，生成一个项目的配置文件。这种功能的原理是怎么实现的呢？

比如：

D:>npm init --yes
Wrote to D:package.json:

{
  "name": "",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "directories": {
    "doc": "doc"
  },
  "scripts": {
    "test": "echo "Error: no test specified" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC"

其实很简单，在之前这篇文章php解释命令行的参数的基础上，加上下面的init分支，即可实现类似的功能

#!/usr/bin/php
<?php
    function init(){
        return file_put_contents( getcwd() . '/go.json', '{}' ) . 'bytes has written.' . 'config file has created';
    }

    $res = '';
    if( $argc >= 2 ) {
        $argv[1] == '-v' && $res = 'go version is 1.0';
        $argv[1] == 'init' && $res = init();
    }
    echo $res . PHP_EOL;

ghostwu@ghostwu:~/mybin$ ls
go2
ghostwu@ghostwu:~/mybin$ go2 init
2bytes has written.config file has created
ghostwu@ghostwu:~/mybin$ ls
go2  go.json
ghostwu@ghostwu:~/mybin$ cat go.json
{}ghostwu@ghostwu:~/mybin$