如何将 STDIN 传递给 node.js 子进程

Question

我正在使用一个为节点包装 pandoc 的库。但我不知道如何将 STDIN 传递给子进程 `execFile...

var execFile = require('child_process').execFile;
var optipng = require('pandoc-bin').path;

// STDIN SHOULD GO HERE!
execFile(optipng, ['--from=markdown', '--to=html'], function (err, stdout, stderr) {
    console.log(err);
    console.log(stdout);
    console.log(stderr);
});

在 CLI 上它看起来像这样：

echo "# Hello World" | pandoc -f markdown -t html

更新 1

尝试让它与 spawn 一起工作：

var cp = require('child_process');
var optipng = require('pandoc-bin').path;
var child = cp.spawn(optipng, ['--from=markdown', '--to=html'], { stdio: [ 0, 'pipe', 'pipe' ] });

child.stdin.write('# HELLO');
// then what?

Answer 1

根据这些 docs 和以下摘录，我不确定是否可以将 STDIN 与 child_process.execFile() 一起使用，看起来它仅适用于 child_process.spawn()

The child_process.execFile() function is similar to child_process.exec() except that it does not spawn a shell. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than child_process.exec().

Answer 2

这是我如何让它工作的：

var cp = require('child_process');
var optipng = require('pandoc-bin').path; //This is a path to a command
var child = cp.spawn(optipng, ['--from=markdown', '--to=html']); //the array is the arguments

child.stdin.write('# HELLO'); //my command takes a markdown string...

child.stdout.on('data', function (data) {
    console.log('stdout: ' + data);
});
child.stdin.end();

Answer 3

喜欢spawn(), execFile() also returns a ChildProcess instance which has a stdin可写流。

作为 write() and listening for the data event, you could create a readable stream, push() your input data, and then pipe() 的替代方法 child.stdin:

var execFile = require('child_process').execFile;
var stream   = require('stream');
var optipng  = require('pandoc-bin').path;

var child = execFile(optipng, ['--from=markdown', '--to=html'], function (err, stdout, stderr) {
    console.log(err);
    console.log(stdout);
    console.log(stderr);
});

var input = '# HELLO';

var stdinStream = new stream.Readable();
stdinStream.push(input);  // Add data to the internal queue for users of the stream to consume
stdinStream.push(null);   // Signals the end of the stream (EOF)
stdinStream.pipe(child.stdin);

Answer 4

作为标准输入的字符串

如果您使用同步方法（execFileSync、execSync 或 spawnSync），您可以使用input 输入选项。像这样：

const child_process = require("child_process");
const str = "some string";
const result = child_process.spawnSync("somecommand", ["arg1", "arg2"], { input: str });

如何将 STDIN 传递给 node.js 子进程

How to pass STDIN to node.js child process

command-line-interface

node.js

作为标准输入的字符串