using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string input = "Microsoft Windows [Version 10.0.14393] (c) 2016 Microsoft Corporation. All rights reserved. C:\\Program Files (x86)\\IIS Express>D:\\sample1.bat C:\\Program Files (x86)\\IIS Express>echo ECHO is on. C:\\Program Files (x86)\\IIS Express>echo \"Select * from Table\" \"Select * from Table\" C:\\Program Files (x86)\\IIS Express>exit";

        Regex findEcho = new Regex("echo (?<echostring>\".*\")", RegexOptions.Compiled);

        var matches = findEcho.Matches(input);

        foreach (Match match in matches) {

            if (match.Success) {

                if (match.Groups["echostring"].Success) {

                    Console.WriteLine(match.Groups["echostring"].Value);

                }

            }

        }

    }

}