如何将Bash命令的输出分配给变量？(How to assign the output of a Bash command to a variable? [duplicate])

 我喜欢返回一个新的集合实例。 这使得这些过滤方法可以链接（例如boxes.byColor("red").bySize("L") ）。 
 
var Boxes = Backbone.Collection.extend({
    model: Box,

    byColor: function (color) {
        filtered = this.filter(function (box) {
            return box.get("color") === color;
        });
        return new Boxes(filtered);
    }
});

var red_boxes = boxes.byColor("red")

I like returning a new instance of the collection. This makes these filtering methods chainable (boxes.byColor("red").bySize("L"), for example).
 
var Boxes = Backbone.Collection.extend({
    model: Box,

    byColor: function (color) {
        filtered = this.filter(function (box) {
            return box.get("color") === color;
        });
        return new Boxes(filtered);
    }
});

var red_boxes = boxes.byColor("red")