Node.js child_process生成自定义stdio [英] Nodejs child_process spawn custom stdio

问题描述

我想使用自定义流来处理child_process.spawn stdio。

I would like to use custom stream to handle child_process.spawn stdio.

例如

const cp = require('child_process');
const process = require('process');
const stream = require('stream');

var customStream = new stream.Stream();
customStream.on('data', function (chunk) {
    console.log(chunk);
});

cp.spawn('ls', [], {
    stdio: [null, customStream, process.stderr]
});

我收到错误 stdio流的值不正确 。

有有关child_process.spawn的文档 https://nodejs.org/api/child_process.html#child_process_options_stdio 。它表示，对于stdio选项，它可以使用Stream对象

There is documentation for child_process.spawn https://nodejs.org/api/child_process.html#child_process_options_stdio. It says for stdio options that it can take Stream object

Stream对象-共享引用tty，文件，套接字或带有子进程的管道。

Stream object - Share a readable or writable stream that refers to a tty, file, socket, or a pipe with the child process.

我想我错过了这个指代部分。

I guess I'am missing this "refers to" part.

推荐答案

似乎是一个错误： https://github.com/nodejs/node-v0.x-archive/issues/4030 customStream 传递给spawn（）时似乎还没有准备好。您可以轻松解决此问题：

It seems to be a bug: https://github.com/nodejs/node-v0.x-archive/issues/4030 The customStream seems to be not ready when it's passed to spawn(). You can go around this issue easily:

const cp = require('child_process');
const stream = require('stream');

// use a Writable stream
var customStream = new stream.Writable();
customStream._write = function (data) {
    console.log(data.toString());
};

// 'pipe' option will keep the original cp.stdout
// 'inherit' will use the parent process stdio
var child = cp.spawn('ls', [], {
    stdio: [null, 'pipe', 'inherit'] 
});

// pipe to your stream
child.stdout.pipe(customStream);

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