PROBE(3PVM)							  PVM Version 3.4						       PROBE(3PVM)

NAME

       pvm_probe - Check if message has arrived.

SYNOPSIS

       C    int bufid = pvm_probe( int tid, int msgtag )

       Fortran	 call pvmfprobe( tid, msgtag, bufid )

PARAMETERS

       tid     Integer task identifier of sending process supplied by the user.

       msgtag  Integer message tag supplied by the user.  msgtag should be >= 0.

       bufid   Integer returning the value of the new active receive buffer identifier.  Values less than zero indicate an error.

DESCRIPTION

       The  routine  pvm_probe	checks	to  see  if a message with label msgtag has arrived from tid.  If a matching message has arrived pvm_probe
       returns a buffer identifier in bufid.  This bufid can be used with pvm_bufinfo to determine information	about  the  message  such  as  its
       source and length.

       If the requested message has not arrived, then pvm_probe returns with a 0 in bufid.  If some error occurs bufid will be < 0.

       A  -1  in msgtag or tid matches anything.  This allows the user the following options.  If tid = -1 and msgtag is defined by the user, then
       pvm_probe will accept a message from any process which has a matching msgtag.  If msgtag =  -1  and  tid  is  defined  by  the  user,  then
       pvm_probe  will accept any message that is sent from process tid.  If tid = -1 and msgtag = -1, then pvm_probe will accept any message from
       any process.

       pvm_probe can be called multiple times to check if a given message has arrived yet. After the message has arrived, pvm_recv must be  called
       before the message can be unpacked into the user's memory using the unpack routines.

EXAMPLES

       C:
	    tid = pvm_parent();
	    msgtag = 4 ;
	    arrived = pvm_probe( tid, msgtag );
	    if ( arrived )
		 info = pvm_bufinfo( arrived, &len, &tag, &tid );
	    else
		 /* go do other computing */

       Fortran:
	    CALL PVMFPROBE( -1, 4, ARRIVED )
	    IF ( ARRIVED .GT. 0 ) THEN
		 CALL PVMFBUFINFO( ARRIVED, LEN, TAG, TID, INFO )
	    ELSE
       *	 GO DO USEFUL WORK
	    ENDIF

ERRORS

       These error conditions can be returned by pvm_probe.

       PvmBadParam
	      giving an invalid tid value or msgtag.

       PvmSysErr
	      pvmd not responding.

SEE ALSO

       pvm_bufinfo(3PVM), pvm_getminfo(3PVM), pvm_nrecv(3PVM), pvm_recv(3PVM), pvm_unpack(3PVM)

								  30 August, 1993						       PROBE(3PVM)