PnetCDF is commonly pre-installed on HPC systems. Typically it is made available through an environment module, so you can activate it with a command like module load pnetcdf.

If PnetCDF is not pre-installed in your particular computing environment, you can install it for your own use on Linux as follows:

1. Download the tar file from: http://cucis.ece.northwestern.edu/projects/PnetCDF/download.html
2. Untar the file (replace <version> with the correct version number so the name matches the name of the file you downloaded):

   $ tar -zxf pnetcdf-<version>.tar.gz

3. Configure and set the installation directory:

   $ ./configure --prefix=<install dir>

4. Build:

   $ make

5. Install:

   $ make install

Note that you need to have a C compiler and MPI library already installed to build PnetCDF.