Move all object in the scene

hi guys,
just need a quick script that moves all objects with the name "track_
to y = -5 (world position) in c#

i have a button made ready to execute this script.
many thanks

using UnityEngine;
using System.Collections;

public class justcheck : MonoBehaviour {
	
	public GameObject[] objectlist;
	// Use this for initialization
	void Start () 
	{
			objectlist = GameObject.FindGameObjectsWithTag("cube");
		
		//objectlist = GameObject.Find("_cube");
	}
	
	// Update is called once per frame
	void Update () 
	{
		if(Input.GetKeyDown(KeyCode.A))
		{
			foreach(GameObject obj in objectlist)
			{
					obj.transform.position =new Vector3(obj.transform.position.x,obj.transform.position.y+2,obj.transform.position.z);
			}
		}
	}
}

//this script work with tag ,all the object with tag = “cube” are collected in array of
gameobject now u can access all object with that array in above script it add the 2 in y dir of every object with tag “cube”!!!