When a process writes to a socket that has received an RST, the SIGPIPE signal is sent to the process. 这是UNIX网络编程卷一(5.13章节)中的内容。但是在实际的编程中发现，当套接字收到RST报文段后，第一次read或者write会产生ECONNRESET错误，第二次read或者write时才会触发SIGPIPE信号。这与UNIX网络编程卷一中的描述“当套接字接收到RST后，我们再执行write操作则会触发SIGPIPE信号”不一样。

The default action of this signal is to terminate the process, so the process must catch the signal to avoid being involuntarily terminated. If the process either catches the signal and returns from the signal handler, or ignores the signal, the write operation returns EPIPE. If special actions are needed when the signal occurs (writing to a log file perhaps), then the signal should be caught and any desired actions can be performed in the signal handler.