how to wall run in unity code example

Example: wall running unity

// Character Controller
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
[RequireComponent(typeof(CharacterController))]
public class PlayerMovement : MonoBehaviour
{
public float walkingSpeed = 7.5f;
public float runningSpeed = 11.5f;
public float jumpSpeed = 8.0f;
public float gravity = 20.0f;
public Camera playerCamera;
public float lookSpeed = 2.0f; 
public float lookXLimit = 45.0f;
CharacterController characterController;
Vector3 moveDirection = Vector3.zero;
float rotationX = 0;
[HideInInspector]
public bool canMove = true;
void Start()
{
characterController = GetComponent<CharacterController>();
// Lock cursor
Cursor.lockState = CursorLockMode.Locked;
Cursor.visible = false;
} 
void Update()
{  
// We are grounded, so recalculate move direction based on axes
Vector3 forward = transform.TransformDirection(Vector3.forward); 
Vector3 right = transform.TransformDirection(Vector3.right); 
// Press Left Shift to run
bool isRunning = Input.GetKey(KeyCode.LeftShift); 
float curSpeedX = canMove ? (isRunning ? runningSpeed : walkingSpeed) * Input.GetAxis("Vertical") : 0;         float curSpeedY = canMove ? (isRunning ? runningSpeed : walkingSpeed) * Input.GetAxis("Horizontal") : 0;
float movementDirectionY = moveDirection.y;
moveDirection = (forward * curSpeedX) + (right * curSpeedY);
if (Input.GetButton("Jump") && canMove && characterController.isGrounded)
{ 
moveDirection.y = jumpSpeed;
} 
else
{
moveDirection.y = movementDirectionY;
} 
// Apply gravity. Gravity is multiplied by deltaTime twice (once here, and once below 
// when the moveDirection is multiplied by deltaTime). This is because gravity should be applied
// as an acceleration (ms^-2)         
if (!characterController.isGrounded)
{ 
moveDirection.y -= gravity * Time.deltaTime;
}          
// Move the controller         
characterController.Move(moveDirection * Time.deltaTime);
// Player and Camera rotation
if (canMove)
{ 
rotationX += -Input.GetAxis("Mouse Y") * lookSpeed;  
rotationX = Mathf.Clamp(rotationX, -lookXLimit, lookXLimit);    
playerCamera.transform.localRotation = Quaternion.Euler(rotationX, 0, 0);  
transform.rotation *= Quaternion.Euler(0, Input.GetAxis("Mouse X") * lookSpeed, 0); 
}
}
}