ultrix man page for shutdown

shutdown(2)							System Calls Manual						       shutdown(2)

Name
       shutdown - shut down full-duplex connection

Syntax
       shutdown(s, how)
       int s, how;

Description
       The call causes all or part of a full-duplex connection on the socket associated with s to be shut down.  If how is 0, further receives are
       disallowed.  If how is 1, further sends are disallowed.	If how is 2, further sends and receives are disallowed.

Return Values
       A zero (0) is returned if the call succeeds, -1 if it fails.

Diagnostics
       The call succeeds unless:

       [EBADF]	      The s argument is not a valid descriptor.

       [ENOTSOCK]     The s argument is a file, not a socket.

       [ENOTCONN]     The specified socket is not connected.

See Also
       connect(2), socket(2)

																       shutdown(2)