Hello thanos1983,

I see three problems in your code (there may be others):

1. You are not saving anything to @xls:

Getopt::Long::GetOptions
(
    'f=s{1,}' => sub
    {
        print "This is the number of \@ARG arguments inside the proces
+s " . @ARGV . "\n";
        print "This is the number of \@xls arguments inside the proces
+s " . @xls  . "\n";
        push @xls, pop @_;    # <-- Add this
    },
    ...
[download]

2. In this condition: if scalar (@xls == 0); the parentheses apply scalar to the result of the == comparison. You need either if (scalar @xls) == 0; or just if scalar @xls == 0; — or drop the scalar altogether: if @xls == 0.

3. If you want to print out the contents of @xls, change

   print "Input given form \@xls: ".@xls."\n";
   [download]

   to

   print "Input given form \@xls: ", join(', ', @xls), "\n";
   [download]

(because concatenation puts @xls into scalar context).

Hope that helps,