(1) log in typhon using your account.
(2) make a new directory with the name of example and then enter the directory. The command will be:

-bash-2.05b$mkdir example
-bash-2.05b$cd example


(3) Create a file with the name of example.c and the content is the following(this is your first parallel program):

#include <mpi.h>
int main(int argc, char **argv) {
int nprocs, mypid;
MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD,&nprocs);
MPI_Comm_rank(MPI_COMM_WORLD,&mypid );
printf("Hello world from process %d of total %d\n",mypid,nprocs);
MPI_Finalize();
}

You can use vi command to create file and type the contents:

-bash-2.05b$ vi example.c
#include <mpi.h>
int main(int argc, char **argv) {
int nprocs, mypid;
MPI_Init(&argc,&argv);
MPI_Comm_size(MPI_COMM_WORLD,&nprocs);
MPI_Comm_rank(MPI_COMM_WORLD,&mypid );
printf("Hello world from process %d of total %d\n",mypid,nprocs);
MPI_Finalize();
}
~

(4)creat a file with the name of lamhosts and the content is the following: 

typhon
compute01
compute03
compute05

For example, you can use vi command to create the file and type the contents: 

-bash-2.05b$ vi lamhosts
typhon
compute01
compute03
compute05
~
~
~
~~
"lamhosts" 4L, 37C written


Note: This file is indicating the processor elements you are going to use. If you want to find more processor names you can use. go to the directory of etc and open the file hosts where all processors' name are listed. In the above file content, except the name of typhon, You can replace any name with other processor's name.

For example, you can use vi or cat command to open the file and you can have the following:

-bash-2.05b$ ls
example
-bash-2.05b$ cd ..
-bash-2.05b$ cd ..
-bash-2.05b$ ls
bin   dev  home    lib         machines  mnt  proc  sbin      tmp  var
boot  etc  initrd  lost+found  misc      opt  root  tftpboot  usr

-bash-2.05b$ cd etc(before you type this command, please use ls command to check if you have directory named etc)

-bash-2.05b$ cat hosts (before you type this command, please use ls commmand to check if you have file named hosts)

The following are the results from the upper command:

# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost

10.0.0.254      typhon.grid.cuny.edu    typhon
163.238.55.103  typhon.grid.cuny.edu    typhon
163.238.35.5    montecarlo.csi.cuny.edu montecarlo
163.238.35.169    bec.csi.cuny.edu bec
10.0.0.01       compute00.grid.cuny.edu compute00
10.0.0.02       compute01.grid.cuny.edu compute01
10.0.0.03       compute02.grid.cuny.edu compute02
10.0.0.04       compute03.grid.cuny.edu compute03
10.0.0.05       compute04.grid.cuny.edu compute04
10.0.0.06       compute05.grid.cuny.edu compute05
10.0.0.07       compute06.grid.cuny.edu compute06
10.0.0.08       compute07.grid.cuny.edu compute07
10.0.0.09       compute08.grid.cuny.edu compute08
10.0.0.10       compute09.grid.cuny.edu compute09
10.0.0.11       compute10.grid.cuny.edu compute10
10.0.0.12       compute11.grid.cuny.edu compute11
10.0.0.13       compute12.grid.cuny.edu compute12
10.0.0.14       compute13.grid.cuny.edu compute13
10.0.0.15       compute14.grid.cuny.edu compute14
10.0.0.16       compute15.grid.cuny.edu compute15
10.0.0.17       compute16.grid.cuny.edu compute16
10.0.0.18       compute17.grid.cuny.edu compute17
10.0.0.19       compute18.grid.cuny.edu compute18
10.0.0.20       compute19.grid.cuny.edu compute19
10.0.0.21       compute20.grid.cuny.edu compute20
10.0.0.22       compute21.grid.cuny.edu compute21
10.0.0.23       compute22.grid.cuny.edu compute22
10.0.0.24       compute23.grid.cuny.edu compute23
10.0.0.25       compute24.grid.cuny.edu compute24
10.0.0.26       compute25.grid.cuny.edu compute25
10.0.0.27       compute26.grid.cuny.edu compute26
10.0.0.28       compute27.grid.cuny.edu compute27
10.0.0.29       compute28.grid.cuny.edu compute28
10.0.0.30       compute29.grid.cuny.edu compute29
10.0.0.31       compute30.grid.cuny.edu compute30
10.0.0.32       compute31.grid.cuny.edu compute31


After you check this file, if you want to go back to your home directory, type the following command:
-bash-2.05b$ cd

(4)booting the processors in the file of lamhosts using the following command:

-bash-2.05b$ lamboot -v lamhosts


You will see the results as follows:

LAM 7.1.2/MPI 2 C++/ROMIO - Indiana University

n-1<9101> ssi:boot:base:linear: booting n0 (typhon)
n-1<9101> ssi:boot:base:linear: booting n1 (compute01)
n-1<9101> ssi:boot:base:linear: booting n2 (compute03)
n-1<9101> ssi:boot:base:linear: booting n3 (compute05)
n-1<9101> ssi:boot:base:linear: finished


(5)compile your parallel program using the following command:

-bash-2.05b$ mpicc example.c -o example


And you will see the result as following:
example.c:9:2: warning: no newline at end of file

(6)Now list all files you have using ls command:

-bash-2.05b$ ls


And you will see the result as follows:

example  example.c  lamhosts

                                
(7) run your parallel program using the following command:

-bash-2.05b$ mpirun -np 4 ./example


And you will see the result similar as follows(the processor sequence may be different):
Hello world from process 0 of total 4
Hello world from process 1 of total 4
Hello world from process 2 of total 4
Hello world from process 3 of total 4