my $buf = delete $self->{buf}; # initial buffer
$buf = $self->{rpipe}->getline unless defined $buf;
$self->{filter} = -1 unless defined $buf; # set EOF for next call
my $buf = delete $self->{buf}; # initial buffer
$buf = $self->{rpipe}->getline unless defined $buf;
$self->{filter} = -1 unless defined $buf; # set EOF for next call