open my $fh, '-|', 'some command';
my $w; $w = AnyEvent->io(
        fh   => $fh,
        poll => 'r',
        cb   => sub {
                chomp(my $user = $fh->getline);
                AnyEvent::XMPP::IM::Message->new(
                        body => construct_body( $msg->body, $from ),
                        to   => "$user\@" . HOST,
                        type => "chat",
                )->send($conn);
                undef $w if eof($fh);
        } );