ok perlmonks, I've got a question. I've made a piece of code:

#!usr/bin/perl

use 5.6.1;

use strict;
use warnings;

use Mail::Internet;
use MIME::Parser;

my $mail = Mail::Internet->new($ARGV[0]);
my $headers = $mail->head()->header_hashref();

my $maximum = 100000;
my $mailnummer = int(rand($maximum));
my $from = $headers->{From}->[0];
my $to = $headers->{To}->[0];

my $cc = $headers->{CC}->[0];
if ($cc eq ""){
$cc = 0;
}

my $date_time = $headers->{Date}->[0];

my $subject = $headers->{Subject}->[0];
if ($subject eq ""){
$subject = 0;
}
    
    my $parser = MIME::Parser->new();

        $parser->output_under('/tmp');
        my $entity = $parser->parse($ARGV[0]);
        my $file;
            if ( $entity->is_multipart ) {
            
                for my $part ( $entity->parts ) {
                my $head = $part->head;
                
                    if ( my $filename = $head->recommended_filename ) 
+{
                        $file = $filename;
                    }
                }
            }
[download]

in this code stands 2 times: $ARGV[0]. I give the command in linux: perl program.txt perltst.

my information is inside perltst for this code. but with this form of the code this will only look at the "word" perltst itself.

in what way can I change $ARGV[0] to get there everything what is inside perltst?