Running MPI programs

mpirun -np 2 hello

mpirun is not part of the standard, but some version of it is common with several MPI implementations. The version shown here is for the MPICH implementation of MPI.
Another Example (Again no messsage-passing) (hello1.c):

#include <stdio.h> 
#include <mpi.h> 
main(argc, argv) 
int argc; 
char *argv[]; 
{ 
char name[BUFSIZ]; 
int length; 
MPI_Init(&argc, &argv); 
MPI_Get_processor_name(name, &length); 
printf("%s: hello world\n", name); 
MPI_Finalize(); 
}