LayerMask.value

public int value ;

Description

Converts a layer mask value to an integer value.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public LayerMask mask = -1;
    void Update() {
        if (Physics.Raycast(transform.position, transform.forward, 100, mask.value))
            Debug.Log("Hit something");
        
    }
}