How to pass STDIN to node.js child process

Question

I\'m using a library that wraps pandoc for node. But I can\'t figure out how to pass STDIN to the child process `execFile...

var execFile = requ         


        

Answer 1

Like spawn(), execFile() also returns a ChildProcess instance which has a stdin writable stream.

As an alternative to using write() and listening for the data event, you could create a readable stream, push() your input data, and then pipe() it to 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);