That prints out the lines containing either or both of "gateway" and "TIMESTAMP". Your if is equivalent to

        if (/gateway/ || /TIMESTAMP/) { 
            $count = $count + 1; 
            print OUT; 
            print "Extracting line ...\n"; 
        }
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However, I was under the impression you want lines containing both. If you want the lines containing both, your if would look like

        if (/gateway/ && /TIMESTAMP/) { 
            $count = $count + 1; 
            print OUT; 
            print "Extracting line ...\n"; 
        }
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As for excluding the listed names, one way is to start by building a regex using one of the following two methods:

my ($exclude_re) = map qr/$_/,
                   join '|',
                   map quotemeta,
                   @names;
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or

use Regexp::List qw( );
my $exclude_re = Regexp::List->new()->list2re(@names);
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The just make sure the line doesn't match that regexp:

        if (/gateway/ && /TIMESTAMP/ && !/$exclude_re/) { 
            $count = $count + 1; 
            print OUT; 
            print "Extracting line ...\n"; 
        }
[download]