Arguments on the command line that follow the application program name and are
not directed to the mpich system (don't begin with -mpi or -p4)
are passed through to all processes of the application program. For example,
if you execute
mpirun -echo -np 4 myprog -mpiversion -p4dbg 10 x y zthen -echo -np 4 is interpreted by mpirun (echo actions of mpirun and run four processes), -mpiversion is interpreted by mpich (each process prints configuration information), -p4dbg 10 is interpreted by the p4 device if your version was configured with -device=ch_p4 (sets p4 debugging level to 10), and x y z are passed through to the application program. In addition, MPI_Init strips out non-application arguments, so that after the call to MPI_Init in your C program, the argument vector argv contains only
myprog x y zand your program can process its own command-line arguments in the normal way.