#include <mpi.h>
#include <stdio.h>
int main( int argc, char ** argv )
{
 MPI_Init( NULL, NULL );
 int world_size;
 MPI_Comm_size( MPI_COMM_WORLD, &world_size );
 int world_rank;
 MPI_Comm_rank( MPI_COMM_WORLD, &world_rank );
 char processor_name[MPI_MAX_PROCESSOR_NAME];
 int name_len;
 MPI_Get_processor_name( processor_name, &name_len );
 printf( "Hello world from processor %s, rank %d" " out of %d processors\n", processor_name, world_rank, world_size );
 MPI_Finalize();
}

/opt/mpich2/gnu/bin/mpicc ./hello.c -o hello

compute-0-0
compute-0-1

/opt/mpich/gnu/bin/mpirun -np 2 -machinefile machines ./hello

 
[user1@cluster ~]$ /opt/mpich2/gnu/bin/mpirun -np 2 -machinefile machines ./mpi_hello_world
Could not chdir to home directory /export/home/user1: No such file or directory
Could not chdir to home directory /export/home/user1: No such file or directory
[proxy:0:0@compute-0-0.local] launch_procs (./pm/pmiserv/pmip_cb.c:687): unable to change wdir to /export/home/user1 (No such file or directory)
[proxy:0:0@compute-0-0.local] HYD_pmcd_pmip_control_cmd_cb (./pm/pmiserv/pmip_cb.c:935): launch_procs returned error
[proxy:0:0@compute-0-0.local] HYDT_dmxu_poll_wait_for_event (./tools/demux/demux_poll.c:77): callback returned error status
[proxy:0:0@compute-0-0.local] [mpiexec@cluster.hpc.org] control_cb (./pm/pmiserv/pmiserv_cb.c:215): assert (!closed) failed
[mpiexec@cluster.hpc.org] HYDT_dmxu_poll_wait_for_event (./tools/demux/demux_poll.c:77): callback returned error status
[mpiexec@cluster.hpc.org] HYD_pmci_wait_for_completion (./pm/pmiserv/pmiserv_pmci.c:181): error waiting for event
[mpiexec@cluster.hpc.org] main (./ui/mpich/mpiexec.c:405): process manager error waiting for completion
[user1@cluster ~]$