How to Recursively Walk the Directory Tree

I can't believe I've never written this up before. Like, I literally can't believe it. I swear I did this a long time ago. Oh, well. Whatever.

I frequently need to search all the files in a directory for a specific text value and I always end up rewriting the same code to do it. Well, no more! Here it is. It's based on a sample from Microsoft.

   1: private static void WalkDirectoryTree(DirectoryInfo root)

   2: {

   3:  FileInfo[] files = null;

   4:  DirectoryInfo[] subDirectories = null;

   5: 

   6:  try

   7:  {

   8:   files = root.GetFiles("*.*");

   9:  }

  10:  catch (UnauthorizedAccessException e)

  11:  {

  12:   Console.WriteLine(e.Message);

  13:  }

  14:  catch (DirectoryNotFoundException e)

  15:  {

  16:   Console.WriteLine(e.Message);

  17:  }

  18: 

  19:  if (files != null)

  20:  {

  21:   foreach (var file in files)

  22:   {

  23:    if (File.ReadLines(file.FullName).SkipWhile(line => !line.Contains("search string")).FirstOrDefault() != null)

  24:    {

  25:     Console.WriteLine(file.FullName);

  26:    }

  27:   }

  28: 

  29:   subDirectories = root.GetDirectories();

  30: 

  31:   foreach (var subDirectory in subDirectories)

  32:   {

  33:    WalkDirectoryTree(subDirectory);

  34:   }

  35:  }

  36: }