Node.js spawning a child process interactively with separate stdout and stderr streams

Question

Consider the following C program (test.c):

#include 

int main() {
  printf(\"string out 1\\n\");
  fprintf(stderr, \"string err 1\\n\");
  ge         


        

Answer 1

I was just revisiting this since there is now a 'shell' option available for the spawn command in node since version 5.7.0. Unfortunately there doesn't seem to be an option to spawn an interactive shell (I also tried with shell: '/bin/sh -i' but no joy). However I just found this which suggests using 'stdbuf' allowing you to change the buffering options of the program that you want to run. Setting them to 0 on everything produces unbuffered output for all streams and they're still kept separate.

Here's the updated javascript:

var TEST_EXEC = './test';

var spawn = require('child_process').spawn;
var test = spawn('stdbuf', ['-i0', '-o0', '-e0', TEST_EXEC]);

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

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

// Simulate entering data for getchar() after 1 second
setTimeout(function() {
  test.stdin.write('\n');
}, 1000);

Looks like this isn't pre-installed on OSX and of course not available for Windows, may be similar alternatives though.