Solved via process.stdin.unref();

Although I think it would be nice to add this to docs, so I'll reopen.

@szmarczak I think instead of hanging, the program is waiting for the end of stdin.
If you start logging what the program reads like the docs say, you will see that it comes to an end after the input is over:

const readline = require('readline');

const input = readline.createInterface({
    input: process.stdin
});

input.on('line', (line) => {
    console.log(line);
})

Here is the log of a run:

❯ time echo 'here is a line'|node index
here is a line
echo 'here is a line'  0.00s user 0.00s system 33% cpu 0.002 total
node index  0.07s user 0.02s system 63% cpu 0.140 total

@szmarczak if still need to address this issue and add this functionality to the doc I would like to take this and open a PR.
Just want to make sure what is being asked... in this API doc I need to add an example as you described? can you maybe give me any advice about in which section do you think that it would be wise to add this example to?

At the end of readline.createInterface(options) section

I have added the example. Please let me know if it needs an update.