Hi, I want to build a program to find out all the "ffn" format from NCBI. The program as followings:

use strict;
use warnings;

use Net::FTP::Find;

use constant NCBI_FTP => "ftp.ncbi.nlm.nih.gov";
use constant BLAST_DB_DIR_VIRUS => "/genomes/Viruses/";
use constant USER => "anonymous";
use constant PASSWORD => "anonymous";

my $ftp;
my $ffn_total; 

$ftp = Net::FTP::Find -> new(NCBI_FTP, Debug => 0)
    or die "Cannot connect to" . NCBI_FTP . ": $@";
    
$ftp -> login (USER, PASSWORD)
    or die "Cannot login to" . NCBI_FTP . ": $@";
    
$ftp -> cwd (BLAST_DB_DIR_VIRUS);

$ftp -> binary();

my @blast_db_files = $ftp->ls();

print "checking the total number of virus files...\n";

$ftp -> find(\&wanted, @blast_db_files);

sub wanted {
if (/^.*\.ffn\z/s) {
    print "$_\n";   
    }
}
[download]

The result from perl released with ubuntu was blank. I debuged it and found the @blast_db_files was empty!!! I tried this on Win where the perl was Activeperl 5.18.2 and found the @blast_db_files were right. @blast_db_files contained the names of the sub-files. How could this happen? Any helps will be appreciated!