SharePoint Online- Rename document Library filename - using client context c#

Dowload code 

using Microsoft.SharePoint.Client;

using System;

using System.Collections.Generic;

using System.Linq;

using System.Security;

using System.Text;

using System.Threading.Tasks;

namespace RenameSPFileDoc

{

    class Program

    {      

        /// <summary>

        /// SharePoint online site connect in c#

        /// </summary>

        /// <param name="args"></param>

        static void Main(string[] args)

        {

            Console.WriteLine("SharePoint Online site URL:");

            string webSPOUrl = Console.ReadLine();

            Console.WriteLine("User Name:");

            string userName = Console.ReadLine();

            Console.WriteLine("Password:");

            SecureString password = FetchPasswordFromConsole();

            try

            {

                using (var context = new ClientContext(webSPOUrl))

                {

                    context.Credentials = new SharePointOnlineCredentials(userName, password);

                    Web web = context.Web;

                    Console.WriteLine("Enter Document Library Name : ");

                    string DocumentName = Convert.ToString(Console.ReadLine());

                    Console.WriteLine("Enter your Folder Name : ");

                    string folederName = Convert.ToString(Console.ReadLine());

                    Console.WriteLine("Enter Prfefix Name : ");

                    string prefixName = Convert.ToString(Console.ReadLine());

                    List list = context.Web.Lists.GetByTitle(DocumentName);

                    context.Load(list);

                    context.Load(list.RootFolder);

                    context.Load(list.RootFolder.Folders);

                    context.Load(list.RootFolder.Files);

                    context.ExecuteQuery();

                    FolderCollection fcol = list.RootFolder.Folders;

                    var folderExists = fcol.Any(x => x.Name == folederName);

                    if (folderExists)

                    {

                        foreach (Folder f in fcol)

                        {

                            if (f.Name == folederName)

                            {

                                context.Load(f.Files);

                                context.ExecuteQuery();

                                FileCollection fileCol = f.Files;

                                foreach (File file in fileCol)

                                {

                                    context.Load(file.ListItemAllFields);

                                    context.ExecuteQuery();

                                    file.MoveTo(file.ListItemAllFields["FileDirRef"] + "/" + prefixName + file.ListItemAllFields["FileLeafRef"].ToString(), MoveOperations.Overwrite);

                                    context.ExecuteQuery();

                                    Console.ForegroundColor = ConsoleColor.White;

                                    Console.WriteLine("Rename : " + file.ListItemAllFields["FileDirRef"].ToString() + "=>" + prefixName + file.ListItemAllFields["FileLeafRef"].ToString());

                                }

                            }

                        }

                    }

                    else

                    {

                        Console.WriteLine("There is no folder name inside doc !!!");

                    }

                }

            }

            catch (Exception ex)

            {

                Console.WriteLine("Error is: " + ex.Message + "Trace is : " + ex.StackTrace);

            }         

            Console.WriteLine("Press any key to continuee...");

            Console.Read();

        }

        private static SecureString FetchPasswordFromConsole()

        {

            string password = "";

            ConsoleKeyInfo info = Console.ReadKey(true);

            while (info.Key != ConsoleKey.Enter)

            {

                if (info.Key != ConsoleKey.Backspace)

                {

                    Console.Write("*");

                    password += info.KeyChar;

                }

                else if (info.Key == ConsoleKey.Backspace)

                {

                    if (!string.IsNullOrEmpty(password))

                    {

                        password = password.Substring(0, password.Length - 1);

                        int pos = Console.CursorLeft;

                        Console.SetCursorPosition(pos - 1, Console.CursorTop);

                        Console.Write(" ");

                        Console.SetCursorPosition(pos - 1, Console.CursorTop);

                    }

                }

                info = Console.ReadKey(true);

            }

            Console.WriteLine();

            var securePassword = new SecureString();

            //Convert string to secure string 

            foreach (char c in password)

                securePassword.AppendChar(c);

            securePassword.MakeReadOnly();

            return securePassword;

        }

    }

}