Simple MPI program which prints rank from each process.

mpi_hello.c

#include<stdio.h>
#include<mpi.h>

int main (char **args, int nargs) {
	MPI_Init (&nargs, &args);
	int rank;
	MPI_Comm_rank (MPI_COMM_WORLD, &rank);
	fprintf (stdout, "Greetings from process of rank %d.\n", rank);
	MPI_Finalize();
	return 0;
}