child1.js

"use strict";

process.title = "child 1"

var fs = require('fs')

var writeStream = fs.createWriteStream(undefined, {fd: 3});

console.log('Child 1!', typeof readStream, typeof writeStream);

setInterval(function(){
    console.log('child ping');
    
    writeStream.write("ping");
}, 600);

setTimeout(function(){
    console.log('child 1 out')
    process.exit();
}, 5*1000);


process.on('uncaughtException', function(err){
    console.error('child', 1, err, err.stack)
});

child2.js

"use strict";

process.title = "child 2";

var fs = require('fs')

var readStream = fs.createReadStream(undefined, {fd: 3});

console.log('Child 2!', typeof readStream, typeof writeStream);

readStream.on('error', function(err){
    console.log("readStream error", err);
});

readStream.on('close', function(err){
    console.log("c2 readStream close", err);
});
readStream.on('end', function(err){
    console.log("c2 readStream end", err);
});

readStream.on('readable', function(){
    readStream.on('data', function(buf){
        console.log('child 2 received', buf.length);
    });
});

setTimeout(function(){
    console.log('child 2 out')
    process.exit();
}, 5*1000);

process.on('uncaughtException', function(err){
    console.error('child', 2, err, err.stack)
});

parent.js

"use strict";

var spawn = require('child_process').spawn;

var child1 = spawn("node", [require.resolve('./child1.js')], {
    stdio: [process.stdin, process.stdout, process.stderr, 'pipe']
});

var child2 = spawn("node", [require.resolve('./child2.js')], {
    stdio: [process.stdin, process.stdout, process.stderr, child1.stdio[3]]
});