#!d:\perl\bin\perl.exe

$pth = "\\\\127.0.0.1\\bex";
opendir(Directory, $pth) or die "Cannot Open Directory";
@contents = grep {
          m!^[Bb].+\.txt$!  #assuming .txt ending
          and
          -M "$path\\$_" > 1
         } readdir(Directory);
closedir(Directory);