Sbappend adds the data at the end of send buffer and tcp_output sends the segment onto the interface.
sbappend在发送缓冲区的末尾添加数据，并且tcp _ out put将该段发送到接口。
2
Therefore, a SONET interface can report B2 errors only for a particular monitored segment.
因此，SONET接口可以报告，只在一个特定监测段B2的错误。
3
In this tutorial segment we'll look at a few ways you can customize controls, and then close out by polishing up the user interface of our Digg application using these techniques.