#!/usr/bin/perl
use CGI;
use strict;
use warnings;
use Net::FTP;
use feature 'say';

my $cgi = CGI->new();
my $file = $cgi->param( 'upload' ) || 'test.pl';

say do_ftp($file);

sub do_ftp {
    my ($filename) = @_;
    return unless $filename ;
}

__END__

$ perl ftp.pl
test.pl