Node JS spawn input text when prompted

Question

I'm using the Node JS Child Process to run a command, I need to somehow automatically enter some text when prompted and press enter automatically from within my stdout, not sure how to do that...

var child = spawn('COMMAND-TO-RUN', {
  shell: true
});

child.stdout.on('data', function (data) {
  // when prompted in the terminal, need to input something automatically from here...
  console.log(data)
  console.log("STDOUT:", data.toString());
});

UPDATE

I've already tried to use child.stdin.write and this didn't work in the context of my problem where the terminal is prompting for a SSH password since I'm trying to automate inputting a password into the terminal through the JS, not sure why this doesn't work.

@shamsup I've already tried this, it doesn't write anything when I'm prompted in the terminal. For context (on a mac terminal) it's trying to connect to a server through SSH and prompts me for the password to that sever after some time. stdin.write appears not to write anything. — Ryan H
– Ryan H, Commented Sep 20, 2020 at 15:31
If you append a '\n' to the input does it work? The line feed signifies the submission of the prompt. — shamsup
– shamsup, Commented Sep 20, 2020 at 15:39
There is probably not a generic way to do that. ssh doesn't read the password from standard input, otherwise something like echo password | ssh host would work. Instead standard input gets passed to the command on the remote side. This may or may not help: serverfault.com/questions/241588/… — Felix Kling
– Felix Kling, Commented Sep 21, 2020 at 14:32

kavigun · Accepted Answer · 2020-09-21 14:40:02Z

1

+50

You can pipe the child's stdin and stderr to the parent process. For example:

var child = spawn('ps', {
    shell: true
});

child.stdout.on('data', function (data) {
    // when prompted in the terminal, need to input something automatically from here...
    process.stdout.write('Something I want to print\n\n');
    console.log(data)
    console.log("STDOUT:", data.toString());
});

edited Sep 21, 2020 at 14:40

answered Sep 21, 2020 at 14:24

kavigun

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1 Comment

kavigun Over a year ago

@ryan-holton, here is the screenshot of the output.

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