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node.js shell command execution

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How can node js program be executed?

The usual way to run a Node. js program is to run the globally available node command (once you install Node. js) and pass the name of the file you want to execute. While running the command, make sure you are in the same directory which contains the app.

How run js file in shell script?

You can Run your JavaScript File from your Terminal only if you have installed NodeJs runtime. If you have Installed it then Simply open the terminal and type “node FileName. js”. If you don't have NodeJs runtime environment then go to NodeJs Runtime Environment Download and Download it.


There are three issues here that need to be fixed:

First is that you are expecting synchronous behavior while using stdout asynchronously. All of the calls in your run_cmd function are asynchronous, so it will spawn the child process and return immediately regardless of whether some, all, or none of the data has been read off of stdout. As such, when you run

console.log(foo.stdout);

you get whatever happens to be stored in foo.stdout at the moment, and there's no guarantee what that will be because your child process might still be running.

Second is that stdout is a readable stream, so 1) the data event can be called multiple times, and 2) the callback is given a buffer, not a string. Easy to remedy; just change

foo = new run_cmd(
    'netstat.exe', ['-an'], function (me, data){me.stdout=data;}
);

into

foo = new run_cmd(
    'netstat.exe', ['-an'], function (me, buffer){me.stdout+=buffer.toString();}
);

so that we convert our buffer into a string and append that string to our stdout variable.

Third is that you can only know you've received all output when you get the 'end' event, which means we need another listener and callback:

function run_cmd(cmd, args, cb, end) {
    // ...
    child.stdout.on('end', end);
}

So, your final result is this:

function run_cmd(cmd, args, cb, end) {
    var spawn = require('child_process').spawn,
        child = spawn(cmd, args),
        me = this;
    child.stdout.on('data', function (buffer) { cb(me, buffer) });
    child.stdout.on('end', end);
}

// Run C:\Windows\System32\netstat.exe -an
var foo = new run_cmd(
    'netstat.exe', ['-an'],
    function (me, buffer) { me.stdout += buffer.toString() },
    function () { console.log(foo.stdout) }
);

A simplified version of the accepted answer (third point), just worked for me.

function run_cmd(cmd, args, callBack ) {
    var spawn = require('child_process').spawn;
    var child = spawn(cmd, args);
    var resp = "";

    child.stdout.on('data', function (buffer) { resp += buffer.toString() });
    child.stdout.on('end', function() { callBack (resp) });
} // ()

Usage:

run_cmd( "ls", ["-l"], function(text) { console.log (text) });

run_cmd( "hostname", [], function(text) { console.log (text) });

I used this more concisely :

var sys = require('sys')
var exec = require('child_process').exec;
function puts(error, stdout, stderr) { sys.puts(stdout) }
exec("ls -la", puts);

it works perfectly. :)


Simplest way is to just use the ShellJS lib ...

$ npm install [-g] shelljs

EXEC Example:

require('shelljs/global');

// Sync call to exec()
var version = exec('node --version', {silent:true}).output;

// Async call to exec()
exec('netstat.exe -an', function(status, output) {
  console.log('Exit status:', status);
  console.log('Program output:', output);
});

ShellJs.org supports many common shell commands mapped as NodeJS functions including:

  • cat
  • cd
  • chmod
  • cp
  • dirs
  • echo
  • exec
  • exit
  • find
  • grep
  • ln
  • ls
  • mkdir
  • mv
  • popd
  • pushd
  • pwd
  • rm
  • sed
  • test
  • which