No input received from terminal

[xerz-one]

I'm developing a simple shell. Because I wanted the execution of code to be synced, input is managed through readline-sync. However, I've found that trying to do anything (including ^C or ^D) is useless. For example, a very basic code like:

rl = require('readline-sync');
input = rl.prompt();

keeps reading without ever responding. The same happens with other commands like rl.question. I can only guess that V8 is unable to receive any input, for some reason.

I'm running a manually compiled node.js 0.10.35 on Ubuntu 14.04 LTS, using Bash and the GNOME Terminal.

[anseki]

Hi, Gomez
Does "keeps reading" mean that a method doesn't return? It's not that receiving a empty text from a method?
That is, The "NEXT LINE" isn't shown by this code?:

var rl = require('readline-sync');
input = rl.prompt();
console.log('NEXT LINE');

[anseki]

And, the prompt text (default: >) is shown?

[xerz-one]

It stops executing at that point, trying to read input and keeping stuck. And the prompt is displayed correctly, so I am a 99'9% sure it has a problem with receiving input.

[anseki]

Ummm... readlineSync works completely on my machine, there seems to be no problem.
(lubuntu-14.04.1, nodejs-v0.10.35, readline-sync-0.4.10)

The setup nodejs was no problem?
Because, I think that it's unusual that the ^C doesn't work.

Try this:

1. Input below, and push enter key.

/bin/sh `node -e "console.log(require('path').dirname(require.resolve('readline-sync')))"`/read.sh

1. Type abc, and push enter key.
2. The abc is shown, and code is finished.

[xerz-one]

That worked! Forgot to mention before - I had the problem while using the Node interpreter. So guess that's what happened. I was executing my code by invoking require() manually, and when I tried to debug, I never ran directly a script (take a look, there was no var when defining a variable)

Now - could this bug be fixed? It seems that the problem is that node.js may be trying to read the input twice, in two different ways simultaneously. Or something like that.

[anseki]

Ah, you tried in REPL. I understood.
The any codes that handles stdin don't work in REPL because REPL handles stdin (TTY). That is, it's like emulating the shell.
This is not bug. This is design of nodejs. And, nobody want input on REPL.

Try this code in REPL:

process.stdin.pause()

[xerz-one]

Ugh, I apologize. How simple. Guess I'll have to study better the APIs!

(and yup, here's someone who wants to read input from REPL. Working on what I consider a cool project. Hi!)

[xerz-one]

Actually -- not working. It still keeps stuck. Here's the source code of the "real" thing:

var os = require('os');
var rl = require('readline-sync');
var child_process = require('child_process');
var sh = require('execSync');

var username = sh.exec("id -un").stdout.replace(os.EOL, '');
var hostname = os.hostname();

module.exports = {
    shell: function (){
        console.log( 'Kuen Shell v0.0.1' );
        console.log( '2015 Francisco Gómez <espectalll123@outlook.com>' + os.EOL );

        process.stdin.pause();
        var loop = true;

        while(loop) {
            rl.setPrompt(username + '@' + hostname + ': ');
            input = rl.prompt();
            try {
                var shExec = sh.exec(input);
                console.log(shExec.stdout);
            } catch(e) {};
        };
    }
}

[anseki]

If you want to read a line from another stream that is not REPL, I think that you must assign another channel (e.g. remote connection).
But, that idea is not good... Because the REPL is used for debug, that is a easy interactive environment. That will spoil REPL's good interactivity.
If you want to make the code run step by step for debug, the node debug might help you. Or, other debug tools like node-inspector.

So, your code seems to run with no problem in my machine. (some syntax errors are shown. but it's running.)
I tried input shell command (e.g. ls), then the response was shown at screen.
Doesn't sh.exec() method fail? because that depends on system environment.

Try this:

var os = require('os');
var rl = require('readline-sync');
var child_process = require('child_process');
//var sh = require('execSync');
// Dummy Object
var sh = {exec: function(cmd) {
    return {stdout: 'Res of: ' + cmd};
}};

var username = sh.exec("id -un").stdout.replace(os.EOL, '');
var hostname = os.hostname();

module.exports = {
    shell: function (){
        console.log( 'Kuen Shell v0.0.1' );
        console.log( '2015 Francisco Gómez <espectalll123@outlook.com>' + os.EOL );

        process.stdin.pause();
        var loop = true;

        while(loop) {
            rl.setPrompt(username + '@' + hostname + ': ');
            input = rl.prompt();
            try {
                var shExec = sh.exec(input);
                console.log(shExec.stdout);
            } catch(e) {};
        };
    }
}

[anseki]

I didn't try running readlineSync on node debug. That result might be same as REPL.

[anseki]

10 days have passed. I think that that problem was already solved, and I close the issue.
If not solved, please reopen it.

[xerz-one]

The bug itself still happens. However, I'm going to try out a different workaround for my idea. Thanks!

[anseki]

Ok. 😊
If that bug you said is the bug of readlineSync, tell me please.

[CreeperDrop]

I don't think that's a bug in readline-sync because it happens also if you try a different loop such as a for loop.

[anseki]

Hi @CreeperDrop, thank you for the comment.

Yes, that is not a bug. It was clearly indicated that there was the problem in @espectalll's environment. (e.g. REPL)