// prints "close" if the z-axis of this transform looks
// almost towards the target

var target : Transform;
function Update () {
    var targetDir = target.position - transform.position;
    var forward = transform.forward;
    var angle = Vector3.Angle(targetDir, forward);
    if (angle < 5.0)
        print("close");
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    public Transform target;
    void Update() {
        Vector3 targetDir = target.position - transform.position;
        Vector3 forward = transform.forward;
        float angle = Vector3.Angle(targetDir, forward);
        if (angle < 5.0F)
            print("close");
        
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    public target as Transform

    def Update():
        targetDir as Vector3 = (target.position - transform.position)
        forward as Vector3 = transform.forward
        angle as single = Vector3.Angle(targetDir, forward)
        if angle < 5.0F:
            print('close')