I have a function that I use for testing a command line application. It uses Node.js child_process.exec to run shell commands, like this:

const proc = child_process.exec(command, { env, timeout }, (error) =>
  errorHandler(error)
);

I then listen to events from proc.stdout and respond to prompts by writing to proc.stdin. I would like to pass SIGINT signal to the child process by writing ASCII characters representing CTRL + C to gracefully stop the process. I have tried ‘^C’ and ‘x03’ but they don’t work. However, piping these characters to the command works:

child_process.exec(`printf '^C' | command`);

What is the difference between these two approaches? Why writing to stdin doesn’t work while piping does?

Note! I’m using the default /bin/sh in Ubuntu (dash). Neither approach works on Windows.