Run shell command as grunt task, like `grunt $:/etc:ls:-laG`, or `grunt $::npm:pack`. Use it with `grunt.task.run('$:blah');`. $:opt_chdir_value:cmd_name:arg1:arg2

grunt-shell.js

module.exports = function(grunt) {
    'use strict';

    var path = require('path');
    var spawn = require('child_process').spawn;

    grunt.registerTask('$', 'Run command in the form $::cmd:arg1:arg2, or $:/blah:cmd:arg.', function() {
        var done = this.async();
        var args = Array.prototype.slice.call(arguments);
        var cwd = process.cwd();
        var chdir = args.shift();
        //make sure it's absolute
        chdir = path.resolve(chdir);

        // ALERT: I know, I know, bad practice, but it works for now
        if (chdir && cwd !== chdir) {
            grunt.log.writeln('From working directory:', path.relative(cwd, chdir).cyan);
            process.chdir(chdir);
        }

        grunt.log.writeln('Spawn:', args.join(' ').cyan);
        spawn(args.shift(), args, {stdio: 'inherit'})
            .on('exit', function (code, signal) {
                done(code != null || code < 1);
            });

        // Restore cwd
        if (chdir && cwd !== chdir) process.chdir(cwd);
    });
};

grunt.registerTask('installfoo', function () {
    grunt.task.run(['$::npm:install:foo']);
});