MESSAGE IPC(2)                   System Calls                   MESSAGE IPC(2)


       procreceive,  procsend,  procrecvclr, procrecvtim - GNO message passing
       IPC system


       #include <gno/gno.h>

       int procsend (pid_t pid, unsigned long msg);
       unsigned long procreceive (void);
       unsigned long procrecvtim (short timeout);
       unsigned long procrecvclr (void);


       These kernel traps comprise GNO's  message  passing  IPC  (interprocess
       communication)  system.   Messages  are unsigned 32-bit data values.  A
       process sends a message to another by using  the  procsend  call.   You
       must specify the process ID of the recipient and the message to pass.

       The  procreceive  trap receives a message.  If no message has been sent
       to the process, the process sleeps until a message arrives.  A  procre-
       ceive  that  is  interrupted by a signal will abort and return -1, with
       errno set to EINTR.

       procrecvclr is used to clear any pending message  a  process  may  have

       procrecvtim  is  similar  to procreceive, but takes a timeout argument,
       specified in 1/10ths of a second.  If no message has been  received  in
       timeout  seconds, procrecvtim fails and returns -1.  The message buffer
       for a process is only one message deep; any attempt to procsend a  mes-
       sage  to a process that already has one queued will result in an error.

       For an IPC system with a deeper queue, see  the  Ports  IPC  man  page,



GNO                            16 December 1996                 MESSAGE IPC(2)

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