use Tie::File;

my $file = '/path/to/file';

tie my @lines,'Tie::File',$file or die $!;
@lines = grep{ is_wanted($_) }@lines;
untie @lines;

sub is_wanted{
    my ($line) = @_;

    my $return = 0;
    if($bedingung_dass_Zeile_erhalten_bleiben_soll){
        $return = 1;
    }
   
    return $return;
}