SOCKET(4)                Series 300 Only                SOCKET(4)

     NAME
          socket - Interprocess communications

     HP-UX COMPATIBILITY
          Level:    HP-UX/NON-STANDARD

          Origin:   UCB

          Remarks:  Implemented on the Series 300 only.

     DESCRIPTION
          Sockets are communication endpoints that allow processes  to
          communicate  either  locally or remotely.  They are accessed
          by means of a set of system calls.  See socket(2).

          The following ioctl(2) requests, defined  in  <sys/socket.h>
          are supported by this version of sockets:

          FIOSNBIO       If the int pointed at by arg is non-zero, the
                         socket   is   put   into  non-blocking  mode.
                         Otherwise,  the  socket  will  be  put   into
                         blocking mode.  Blocking mode is the default.
                         See  accept(2),  connect(2),   recv(2),   and
                         send(2)   for  an  explanation  of  how  non-
                         blocking mode is used.

          FIONREAD       The number of bytes currently  readable  from
                         this socket is returned in the int pointed to
                         by arg.

          The fcntl(2) O_NDELAY flag is supported by sockets.  If  the
          O_NDELAY  flag  is  set,  then read(2)/recv(2) requests will
          always return immediately.  If no data  was  available,  and
          the  request  would  thus normally have blocked, the request
          returns with a bytecount of zero,  which  is  equivalent  of
          returning an EOF condition.

          Since both the fcntl(2) O_NDELAY flag and ioctl(2)  FIOSNBIO
          flag  are  supported,  some  clarification  on how these two
          calls interact is necessary.  If the O_NDELAY flag has  been
          set,  then read(2)/recv(2) requests will behave accordingly,
          regardless of the state of the FIOSNBIO flag.   If  O_NDELAY
          has  not  been  set,  then  the  FIOSNBIO  flag controls the
          behavior of the read(2)/recv(2) requests.

     SEE ALSO
          fcntl(2), ioctl(2), socket(2).

     Hewlett-Packard               - 1 -             (printed 7/16/86)