use File::Find::Rule

sub fullPathToFile #($StartDirectory,$SearchExpression)
{
    my ($StartDirectory,$SearchExpression)= @_;
    my(@files,$IsWin1,$IsWin2,@File_Paths,$Fl,@d,$c);
    @files = File::Find::Rule->file()->name("$SearchExpression")->in("$StartDirectory");
    $IsWin1=substr($StartDirectory,1,1);
    $IsWin2=substr($StartDirectory,0,2);
      #If $StartDirectory starts with D:\ or \\\\ than it is Win replace / with \
      if(($IsWin1 eq ':')||($IsWin2 eq '\\\\'))
	  {
        foreach $Fl (@files) 
		{
          @d=split(/\//,$Fl);
          $c=join ("\\",@d);
          push(@File_Paths,$c);
        }
      }
      else
	  {
        @File_Paths=@files;
      }
return @File_Paths;
}

$LocationOfTheStartDir='C:\chat';
$SearchExp='*.htm';
@AllFilePaths=fullPathToFile($LocationOfTheStartDir,$SearchExp);

foreach $InputFile (@AllFilePaths){
@AllLinesFromTheFile = `type $InputFile`;
	foreach $line (@AllLinesFromTheFile){
		if ($line=~/DesiredString/){
			print "$line";
		}

	}
@AllLinesFromTheFile=();
}