Getting the package

1. Change working directory to the location where you'll build the package. A convenient location is /scratch/$USER, which we'll use for this example. cd /scratch/$USER

2. OpenMPI can be found at https://www.open-mpi.org/software/ompi/. This will automatically redirect you to the latest version, but older releases can be seen in the left menu bar. For this, choose version 4.1.

3. There are several packaging options. Here, we'll get the bzipped tarball openmpi-4.1.0.tar.bz2. You can either download it to a local machine (laptop) and then scp the file over to the HPC cluster, or get it directly on the supercomputer using wget.

   wget https://download.open-mpi.org/release/open-mpi/v4.1/openmpi-4.1.0.tar.bz2
   

   You should now have a compressed tarball in your scratch directory.

4. List the contents of the tarball before unpacking. This is very useful to avoid inadvertently filling a directory with gobs of files and directories when the tarball has them at the top of the file structure),

   tar -tf openmpi-4.1.0.tar.bz2
   

5. Unpack it via

   tar -xjf openmpi-4.1.0.tar.bz2
   

   If you're curious to see what's in the file as it unpacks, add the -v option.
6. You should now have an openmpi-4.1.0 directory. cd openmpi-4.1.0, at which point you are in the top level of the package distribution. You can now proceed to configuring, making, and installing.