why shutdown report error?

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http://stackoverflow.com – on Linux I tried the steps below: create TCP socket, and connect to any HTTP server send HTTP request data shutdown write with SHUT_WR read from socket to get the HTTP response shutdown read with SHUT_RD close the socket here error occurred in step 5, with errno=ENOTCONN. The same error hit me when I tried shutdown Write after reading EOF. Is this expected? (HowTos)