Node.js Is it possible to write to a child process that has been detached

Question

Using Node.js is it possible to write to a process that has been detached?

I have a Node app that runs a process via child_process and then detaches. But later on if I wanted to send a command to that process how would that be achieved with child_process or any other package? Any information would be great thanks.

Answer 1

You can set an event handler for process.on('message') to receive messages from the master in the child_process script, and receive messages from the child_process instance by listening to the child.on('message') event.

Example:

child.js

process.on('message', function(message) {
  process.send('Hey you sent ' + m);
});

master.js

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

var worker = fork('./worker.js');

child.on('message', function(m) {
   console.log('Recieved: ' + m);
});

// we could send as many messages as we want, the child process will 
// will idle between messages
child.send('Message 1');

// Whenever you're done you can kill the child process
child.kill() // Default signal is `SIGTERM`

Answer 2

Via the child_process API this is not possible.

If you are willing to use IPC and/or Unix domain sockets, consider this SO post: sending commands to a process in the background .