CODEWITHSUNDEEP
node.jsshell
Lime
Lime

Reputation: 13569

Use Node.js as Shell

How might I set up node.js as a shell replacement for bash? For example I should be able to run vi('file') to open a file and cd('location') to change between directories.

Is this even possible?

Upvotes: 3

Views: 4039

Answers (5)

TheHans255
TheHans255

Reputation: 2235

Sure you can! It will become much less straightforward to use your computer, though.

First off, you will need to know how to set this up. While you could likely set your user shell in Linux to usr/bin/node, this will leave you with only a Node.js REPL with no additional programs set up. What you're going to want to do is write a setup script that can do all of the below setup/convenience steps for you, essentially something that ends with repl.start() to produce a REPL after setting everything up. Of course, since UNIX shell settings can't specify arguments, you will need to write a small C program that executes your shell with those arguments (essentially, exec("/usr/bin/node", "path/to/setup/script.js");) and set that as your UNIX shell.

The main idea here is that any commands that you use beyond the very basics must be require()d into your shell - e.g. to do anything with your filesystem, execute

var fs = require("fs")

and do all of your filesystem calls from the fs object. This is analogous to adding things to your PATH. You can get basic shell commands by using shelljs or similar, and to get at actual executable programs, use Node's built-in child_process.spawnSync for a foreground task or child_process.spawn for a background task.

Since part of your requirement is that you want to call each of your programs like a function, you will need to produce these functions yourself, getting something like:

function ls(path) {
    child_process.spawnSync('/bin/ls', [path], { stdio: 'inherit' });
}

for everything you want to run. You can probably do this programmatically by iterating through all the entries in your PATH and use closures to generate execute functions for each, assigning them to the global object so that you don't have to enter any prefixes.

Again, it will become much less straightforward to use your computer, despite having these named functions. You will need to use sh/bash/zsh explicitly in order to run shell commands you find on the Internet, and programs that specifically call up your user shell and expect it to be Bash-compatible (or if you're on a system where /bin/sh links to your user shell somehow) will no longer work. But I can certainly see the appeal of being able to leverage JavaScript in your command-line environment.

ADDENDUM: For writing this setup script, the REPLServer object returned by repl.start() has a context object that is the same as the global object accessible to the REPL session it creates. When you write your setup script, you will need to assign everything to the context object:

const context = repl.start('> ').context;
context.ls = function ls(path) { /* . . . */ }
context.cd = function cd(path) { /* . . . */ }

Upvotes: 11

Saulo Castelo Sampaio
Saulo Castelo Sampaio

Reputation: 25

I think you're looking for something like this https://youtu.be/rcwcigtOwQ0 !

If so.... YES you can!

If you like I can share my code. But I need to fix some bugs first!

tell me if you like.

my .sh function:

const hey = Object.create(null),
    sh = Object.create(null);;
  
hey.shell = Object.create(null);
hey.shell.run = require('child_process').exec;

sh.help = 'Execute an OS command';
sh.action = (...args) => {
    // repl_ is the replServer
    // the runningExternalProgram property is one way to know if I should 
    //       render the prompt and is not needed. I will create a better
    //        way to do this (action without if/decision)!
    repl_.runningExternalProgram = true;
    hey.shell.run(args.join(' '),
            (...args) => {
                ['error', 'log'].forEach((command, idx) => {
                    if (args[idx]) {
                        console[command](args[idx]);
                    }
                });
                repl_.runningExternalProgram = false;
            });
};

PS: to 'cd' into some directory you just need to change the process.cwd (current working directory)

PS2: to avoid need to write .sh for every OS program/command you can use Proxy on the global object.

Upvotes: -1

Ray Foss
Ray Foss

Reputation: 3883

You could bootstrap a repl session with your own commands, then run the script

#!/bin/bash
node  --experimental-repl-await -i -e "$(< scripts/noderc.js)"`

This allows for things like:

> ls()
> run('vi','file.txt')
> await myAsyncFunc()

Upvotes: 0

Lime
Lime

Reputation: 13569

This works on mac and linux.

require('child_process').spawnSync('vi', ['file.txt'], { stdio: 'inherit' })

Upvotes: 0

jas-
jas-

Reputation: 1801

I think it would be an intersting proposition. Create a test account and tell it to use node as it's shell. See 'man useradd' for all options

$ useradd -s /usr/bin/node test
$ su - test

Upvotes: 1

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