exec.js

var express = require('express');
var app = express();

var exec = require('child_process').exec,
    child;

app.use(express.bodyParser());

app.post('/', function(req, res){
    var cmd = req.body.cmd || '';

    switch (cmd){
        case 'ls':
            execCmd('ls -al ~/');
            break;
        case 'ps':
            execCmd('ps aux | grep node');
            break;
        default:
            execCmd('w');
            break;
    }

    execCmd(cmd);
    res.send('');
});

app.listen(5001);


function execCmd (argument) {
    child = exec(argument,
      function (error, stdout, stderr) {
        console.log('stdout: ' + stdout);
        console.log('stderr: ' + stderr);
        if (error !== null) {
          console.log('exec error: ' + error);
        }
    });
}