process.stdin.setEncoding('utf8')

process.stdin.on('readable', function() {
	var input = process.stdin.read();
	if (input !== null) {
		process.stdout.write(input)
		var command = input.trim();
		if (command == 'exit') {
			process.exit(0);
		}
	}
})

node tmp.js

process.stdin.setEncoding('utf8')
process.stdin.on('data', function(input) {
    if (input !== null) {
        process.stdout.write(input)
        if ( input.trim() === 'exit') {
            process.exit(0);
        }
    }
})

process.stdin.setEncoding('utf8')

process.stdin.on('readable', function() {
  var input = process.stdin.read();
  if (input !== null) {
    process.stdout.write(input);
    var command = input.trim();
    if (command == 'exit') {
      process.exit(0);
    }
    process.stdin.resume()
  }
})