I assume you are searching for filenames and not the content of the files?

Have you tried File::Find?

our   @filelist = ();
our $fdir = "/usr/blah"
find(\&wanted, $fdir);
  die " cannot get file list: $!" unless(@filelist>0);

#assuming the directory exists, @filelist now has all files in blah in
+cluding subdirs.

 sub wanted {
        my $thisfile = $File::Find::name;
        push(@filelist, $thisfile)

        }
[download]

See the doc for how to search using more complex criteria