# 9.5. Launching only on the local node

It is common to develop applications on a single workstation or laptop, and then move to a larger parallel / HPC environment once the application is ready.

PRRTE supports running multi-process jobs on a single machine. In such cases, you can simply avoid listing a hostfile or remote hosts, and simply list a number of processes to launch. For example:

    shell$ prterun -n 6 mpi-hello-world
    Hello world, I am 0 of 6 (running on my-laptop))
    Hello world, I am 1 of 6 (running on my-laptop)
    ...
    Hello world, I am 5 of 6 (running on my-laptop)

If you do not specify the `-n` option, `prterun` will default to launching as many processes as there are processor cores (not hyperthreads) on the machine.