How to modify the previous line of console text?

You can move cursor wherever you want: Console.SetCursorPosition or use Console.CursorTop.

Console.SetCursorPosition(0, Console.CursorTop -1);Console.WriteLine("Over previous line!!!");

Use a carriage return. This sample prints a single line, overwriting what was there before.

  Console.WriteLine();  for (int i = 0; i <= 100; i++)  {    System.Threading.Thread.Sleep(10);    Console.Write("\x000DProgress: " + i);  }

This works as long as all your strings are less than 80 columns (or whatever your terminal buffer is set to).

Note: the following answer was originally edited into the question by the OP.

Here's complete solution with demo:

using System;using System.Collections.Generic;using System.Threading;namespace PowerConsole {    internal class Containers {        internal struct Container {            public int Id;            public int X;            public int Y;            public string Content;        }        public static List<Container> Items = new List<Container>();        private static int Identity = 0;        public static int Add(string text) {            var c = new Container();            c.Id = Identity++;            c.X = Console.CursorLeft;            c.Y = Console.CursorTop;            c.Content = text;            Console.Write(text);            Items.Add(c);            return c.Id;        }        public static void Remove(int id) {            Items.RemoveAt(id);        }        public static void Replace(int id, string text) {            int x = Console.CursorLeft, y = Console.CursorTop;            Container c = Items[id];            Console.MoveBufferArea(                c.X + c.Content.Length, c.Y,                Console.BufferWidth - c.X - text.Length, 1,                c.X + text.Length, c.Y            );            Console.CursorLeft = c.X;            Console.CursorTop = c.Y;            Console.Write(text);            c.Content = text;            Console.CursorLeft = x;            Console.CursorTop = y;        }        public static void Clear() {            Items.Clear();            Identity = 0;        }    }    internal class Program {        private static List<Thread> Threads = new List<Thread>();        private static void Main(string[] args) {            Console.WriteLine("So we have some threads:\r\n");            int i, id;            Random r = new Random();            for (i = 0; i < 10; i++) {                Console.Write("Starting thread " + i + "...[");                id = Containers.Add("?");                Console.WriteLine("]");                Thread t = new Thread((object data) => {                    Thread.Sleep(r.Next(5000) + 100);                    Console.ForegroundColor = ConsoleColor.Green;                    Containers.Replace((int)data, "DONE");                    Console.ResetColor();                });                Threads.Add(t);            }            Console.WriteLine("\n\"But will it blend?\"...");            Console.ReadKey(true);            i = 0;            Threads.ForEach(t => t.Start(i++));            Threads.ForEach(t => t.Join());            Console.WriteLine("\r\nVoila.");            Console.ReadKey(true);        }    }}