Select Code to Download

find sub {
   my $numb = (fileparse($_,'.txt'))[0];
   return unless $numb =~ /^\d+$/;
   push @ARGV, $File::Find::name if $numb >= $start and $numb <= $end;
}, $dir;

opendir DIR, $dir or die "Failed to open directory $dir: $!";
foreach my $file (readdir DIR)
...

    push @ARGV, "$dir/$file";
}

{
    local $, = "\n";
    print @ARGC;
}