MPI parallel programs are written with conventional languages like, C and Fortran  .One or more header files such as "mpi.h" may be needed to give the necessary definitions and declarations. Like other serial program, programs using MPI require to be compiled first before running the program. The command to compile the program may differ according to the compiler being used. If we are using mpcc compiler, then we can run a C program named "program.c"  using the following command:

mpcc  program.c -o program.o

Most executions gives command, typically named mpirun for spawning MPI processes. It gives facilities for the user to select number of processes and which processors they will compile on. For example to run the object file "program" as n processes on n processors we use the following command:

mpirun program -np n