Send data over the transport connection with write(). tirdwr passes data through to the transport provider. If you send a zero-length data packet, which the mechanism allows, tirdwr discards the message. If the transport connection is aborted (for example, because the remote user aborts the connection using t_snddis()), a hang-up condition is generated on the stream, further write() calls fail, and errno is set to ENXIO. You can still retrieve any available data after a hang-up.