gistfile1.txt

    function determineRubyCommandToUse(done) {
        // check to see if native ruby is available, call back with executable name to use
        child_process.exec('ruby -v', function (error) {
            if (error) {
                done('java -jar lib/jruby.jar');
            }
            done('ruby');
        });
    }

    function ruby(commandLineArgs, done) {
        determineRubyCommandToUse(function (command) {
            child_process.exec(command + ' ' + commandLineArgs, done)
        });
    }

    grunt.registerTask('ruby-version', function () {
        var done = this.async();
        ruby('-v', function (error, stdout, stderr) {
            console.log(stdout);
            done();
        });
    });