#!/usr/bin/perl

use strict;
use warnings;

my $PATHDATA = ".";  # (you didn't say how this was being set)

my ( $query_list_file, $file_to_search ) = ( @ARGV == 2 ) ?
    @ARGV :
    ( "$PATHDATA/query04.txt", "$PATHDATA/multisearch_final_sorted_3.txt" );

open( HH, "<", "$PATHDATA/$query_list_file") or die "$PATHDATA/$query_list_file: $!\n";
chomp( my @query_arr = <HH> );
close HH;

my $query_regex = join( '|', @query_arr );

open(XX, "<", "$PATHDATA/$file_to_search") or die "$PATHDATA/$file_to_search: $!\n";
open(DD, ">", "$PATHDATA/query_results.txt") or die "$PATHDATA/query_results.txt: $!\n";
my $count=0;

while ( <XX> ) {
    if ( /^($query_regex)\]/ ) {
        print DD "############\nQUERY: $1\nMATCH: $_\n";
        $count++;
    }
}
print DD "Entrate trovate: $count\n";