#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;


my %keepList;

while (my $line = <DATA>) 
{
   my $sdf_file;
   next unless ($sdf_file) = $line =~ /(\w+\.nfo)/;
   $keepList{$sdf_file} = 1;
   print "keeping $sdf_file\n"; #update for debugging #######
}

=example printout
keeping filename1.nfo
keeping filename2.nfo
=cut

__DATA__
fullpath="C:\directory\filename1.nfo"
id="1a"
fullpath="C:\directory\filename2.nfo"