srcspider / cmdspawn

Promise based command spawner node module

cmdspawn is an easy to use terminal command executor that spawns a command in the background and returns a Promise to it; bluebird is used as the promise library.

npm install cmdspawn

Using a package.json to manage dependencies?

• npm i -D cmdspawn to install
• npm rm -D cmdspawn to uninstall

USAGE

Running cmdspawn gives you a function that can execute commands, using the given configuration you provided to cmdspawn. The executor instance you are given accepts anything from arrays, variable parameters or just a plain string. In all cases the input is converted to a string (joined with spaces if necesary) and executed.

The bluebird Promise library in use is available via the cmdspawn.Promise. See: Bluebird API for helper functions. If you just care for basic methods like then you don't really need to worry about that.

Sometimes a callback function is required. To keep code nice and clean you can use the functor .fin on the instance and pass it the cb parameter, a function that calls the callback and echo'es a empty line on the console will be created for you. See advanced example for use case.

Minimal Example

var cmdspawn = require('cmdspawn');

var cmd = cmdspawn({
	tracking : false, // show start and end of command
	verbose  : true   // write executed commands to console
});

// the following are all equivalent
// use whatever is easier in your code

cmd('ls -la');
cmd('ls', '-la');
cmd(['ls', '-la']);

Should probably be noted that all the above execute in parallel. They will not block, you'll have to use the promise object they return if you want to sync them.

Advance Example: A Basic Gulp C++ Compiler

mkdir build
mkdir src
touch src/main.cc

#include <iostream>

using namespace std;

int main () {
	auto msg = "hello, world";
	cout << msg << endl;
	return 0;
}

echo "{}" > package.json
sudo npm i -g gulp@3
npm i -D gulp@3
npm i -D cmdspawn@1
touch gulpfile.js

var gulp     = require('gulp');
var cmdspawn = require('cmdspawn');
// ----------------------------------------------------------------------------

var cmd = cmdspawn({
	tracking : false, 
	verbose  : true
});

var Compiler = 'g++ -std=c++11';

var compile = function (src, dest) {
	return cmd(Compiler, '-o', dest, '-c', src);
};

var link = function (files, dest) {
	return cmd(Compiler, '-o', dest, files.join(' '));
};

gulp.task('default', function (cb) {
	compile('src/main.cc', 'build/main.o')
		.then(function () {
			link(['build/main.o'], 'build/app')
				.then(cmd.fin(cb))
		});
});

There's always the posibility when dealing with promises that you don't quite call things in the right order or don't sync them, if you encounter cases where that appears to happen simply enable tracking and you'll clearly see what's not syncing up.