Ruby subprocess with node.js

Question

I'm trying to launch a ruby instance as subprocess of my node program. In fact, everything is OK but I just can't interact with the ruby's STDIN and STDOUT. (of course the ruby program works in my terminal with my keyboard input)

So this is a simplified code that I want to get working ...

simpleproc.js

var util   = require('util'),
    spawn = require('child_process').spawn,
    ruby  = spawn('ruby', [__dirname + '/process.rb']);

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

ruby.stderr.on('data', function (data) {
  console.log('stderr: ' + data);
});

ruby.on('exit', function (code) {
  console.log('child process exited with code ' + code);
});

ruby.stdin.write("ping\n");

process.rb

f = File.new("process.log", "w")
f.write "=== Hello! ===\n"
STDIN.each_line do |line|
   STDOUT.write line
   f.write line
end

What's wrong with it ? I've already managed to get an another process working... but here, there is no IO ! Nothing happens !

EDIT: I modified the ruby file to show that, with node, the file is only written with === Hello! ===\n inside. So we can say that, the ruby file is correctly launched but doesn't receive anything from node (I've tried to flush after the STDOUT.write but the do statement is never executed.

Answer 1

Try STDOUT.flush on the ruby side after STDOUT.write, as the output is being buffered.