as i understand: store the line number in a hash instead, so 
my %lines = map { ($_, 1) } qw/1 3 5 7/;  
open(IN, "<grep") or die;
while (<IN>) {
   print OUT $_ if $lines{$.};
}

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HTH

In reply to Re: printing specific lines by esskar
in thread printing specific lines by Anonymous Monk

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