Nodejs Child Process: write to stdin from an already initialised process

I am trying to spawn an external process `phantomjs` using node's `child_process` and then send information to that process after it was initialized, is that possible?

I have the following code:

var spawn = require('child_process').spawn,
child = spawn('phantomjs');

child.stdin.setEncoding = 'utf-8';
child.stdout.pipe(process.stdout);

child.stdin.write("console.log('Hello from PhantomJS')");

But the only thing I got on the stdout is the initial prompt for phantomjs console.

phantomjs>

So it seems the `child.stdin.write` is not making any effect.

I am not sure I can send additional information to phantomjs ater the initial spawn.

You need to pass also `\n` symbol to get your command work:

var spawn = require('child_process').spawn,
child = spawn('phantomjs');

child.stdin.setEncoding('utf-8');
child.stdout.pipe(process.stdout);

child.stdin.write("console.log('Hello from PhantomJS')\n");

child.stdin.end(); /// this call seems necessary, at least with plain node.js executable

You need to surround your `write` by `cork` and `uncork`, the `uncork` method flushes all data buffered since `cork` was called. `child.stdin.end()` will flush data too, but no more data accepted.

```js
var spawn = require('child_process').spawn,
child = spawn('phantomjs');

child.stdin.setEncoding('utf-8');
child.stdout.pipe(process.stdout);

child.stdin.cork();
child.stdin.write("console.log('Hello from PhantomJS')\n");
child.stdin.uncork();
```