my ($prch,$pid) = @_;

##</code><code>##

sub component_window {
    my ($prch,$pid) = @_;
    ...
    my $tail = Tk::IO->new( 
       -linecommand => sub { tail_lines($prch, $_[0]) });
    ...
}

sub tail_lines {
    my ($proc,$text) = @_;
    ...
}
##</code><code>##

sub component_window {
    my ($prch,$pid,$text)=@_;
    ...
##</code><code>##

    ...
    my $tail = Tk::IO->new( 
       -linecommand => sub { tail_lines($prch, $text) });
    ...
}